1. Field
The present disclosure relates generally to communication systems, and more particularly, to activating and deactivating semi-persistent scheduling for VoIP service in LTE and High Speed Packet Access (HSPA) networks.
2. Background
Wireless communication systems are widely used to provide a variety of communication services such as voice, data, broadcast, and others. These communication systems may be multiple-access systems supporting simultaneous resource use by multiple users. This resource sharing is accomplished through the use of shared system resources, including bandwidth and transmit power. A number of multiple access systems are currently in use and include code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), and orthogonal frequency division multiple access (OFDMA). These access systems may be used in conjunction with various communication standards such as those promulgated by 3GPP Long Term Evolution (3G LTE). LTE is an emerging telecommunication standard and is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). It is designed to better support mobile broadband Internet access by improving spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards using OFDMA on the downlink (DL), single carrier frequency division multiple access (SC-FDMA) on the uplink (UL), and multiple-input multiple-output (MIMO) antenna technology.
Wireless multiple access communication systems typically support multiple wireless terminals. Each wireless terminal, also known as a mobile device or user equipment (UE), communicates with one or more base stations using forward and reverse links. The forward link refers to communication link from the base stations to the mobile terminals or UEs, and may also be known as the downlink. The reverse link refers to the communication link from the UEs to the base stations (BS). The communication link may be established by a single link system or a MIMO system.
The traffic generated by the UEs and BSs is managed in part by a serving network controller, which serves as the arbiter of wireless traffic. The network controller can send control information to UEs, assign wireless resources to UEs, manages uplink and downlink interference, and coordinates MIMO transmissions among neighboring BSs. The serving network controller acts as a central planner for managing the disparate wireless communications and ensures consistency and reliability.
One communication standard, 3GPP defines a mechanism known as Semi-Persistent Scheduling (SPS) that eliminates the need for a Physical Downlink Control Channel (PDCCH) resource for each uplink and downlink resource grant. When there is a large number of voice over internet protocol (VoIP) users, the overhead becomes a limiting factor for efficient system operation. The 3GPP specification does not define an activation and deactivation triggering mechanism for SPS, nor does it specify the conditions of SPS activation and deactivation. There is a need in the art for a method and apparatus for determining when to activate and deactivate uplink SPS on both uplink and downlink for an LTE VoIP radio bearer based upon the state of the eNB ROHC decompressor and compressor.